Abstract: Objective
To investigate the nutritional status of vitamin D in children in Ordos area in order to provide basis for rational clinical supplementation of vitamin D.
Methods
Totally 1 572 healthy children aged 29 days to 18 years living in Ordos were included in this study, who took routine physical examination in our hospital from August 2016 to August 2018. Serum 25-hydroxy vitamin D(25-(OH)D) level was measured by electrochemiluminescence.
Results
Vitamin D deficiency existed in 779 cases(49.56%), vitamin D insufficiency in 576 cases(36.64%), and vitamin D sufficiency in 217 cases(13.80%) in the 1 572 subjects. Vitamin D deficiency and insufficiency were more obvious with the increase of age. Before 9 months of age, the vitamin D level increased with the increase of month age, and reached the peak between 9 and 12 months; and after 1 year of age the vitamin D level decreased continuously with the increase of age. There was no significant difference in 25-(OH)D level or vitamin D deficiency and insufficiency rate between boys and girls(P>0.05). The serum 25-(OH)D level was the highest in autumn and the lowest in winter(P<0.05), but there was no significant difference in other seasons(P>0.05).
Conclusion
The levels of 25-(OH)D in children aged 29 days to 18 years old in Ordos area are low, and vitamin D deficiency and insufficiency in children is common.

Key words: Vitamin D deficiency, Vitamin D insufficiency, 25-hydroxy vitamin D, Children